The Uncanny X-Men are a superhero team of mutants that were founded by fellow mutant Professor Charles Xavier. They are dedicated to helping fellow mutants and sworn to protect a world that fears and hates them.

Apocalypse is an old woman? What the heck?

I picked up an issue of Adventures of Cyclops and Phoenix. They're in the future with Nate..

Every shot of Apocalypse, it looks like his entire body is just a big robotic shell, and inside is this shriveled old lady. Then he goes on and talks about how he's burning through his host bodies too fast.

...So uh, has Apocalypse ALWAYS been this way? Is his outside body really just a big robot, and he just steals human bodies to host him inside this armor? If so, how did this happen and why? If not.. well, what the heck is going on in that future that made him this way?

Apocalypse was not always portrayed this way (he used to just use a Lazarus Chamber to put him in stasis and strengthen him when he became weak), and some writers choose to ignore it, but yes, he technically needs host bodies.... sometimes. The entire arc "The Twelve" was devoted to apocalypse trying to get the twelve most powerful mutants on Earth together and trick them into transferring his essence into Nate Grey. During this arc, we see a similar portrayal of him as a shriveled old man, with what appears to be an exoskeleton. Personally, I think it's a stupid idea, especially since Apocalypse has control over his molecular structure, and is backed by Celestial tech (as well as the Celestials, as it turns out). Cyclops ended up playing host to Apocalypse, and wondered the desert for some time, fighting for control. Jean and Cable track him down and exorcise Apocalypse, seemingly getting rid of him forever. Then he just shows up with no explanation years later in the Blood of Apocalypse arc, with nary a mention of host bodies. In Cable & Deadpool it is actually revealed that the T/O virus is what keeps Apocalypse going, and furthermore, that Cable is the one who infected him with it. Hope that clears things up a bit. If not, feel free to post more questions, I'll try to answer them as best I can.